Barotrauma effects on fishes in response to impulsive pile driving stimuli

We report on new results from controlled exposure studies of impulsive pile driving stimuli using the High Intensity Controlled Impedance Fluid Filled Wave Tube (HICI-FT). Following upon initial investigations focusing on injury thresholds and recovery from injuries in the Chinook salmon, experiments have been expanded to include lake sturgeon, Nile tilapia, hybrid striped bass, and hogchoker. Several key questions concerning pile driving exposure in fishes have been explored utilizing species with different types of swim bladders as well as a species without a swim bladder. Injury thresholds were evaluated in all species, with recovery from injuries measured in the hybrid striped bass. Other pile driving variables measured with the hybrid striped bass include difference in response between fish less than or greater than 2g as well as the minimum number of pile strikes needed for injuries to appear. A study to evaluate potential damage to inner ear hair cells was also conducted on hybrid striped bass as well as the Nile tilapia. These studies will be utilized to better understand, and possibly predict, the potential effects of pile driving exposure in fishes.